The human antiviral factor TRIM11 is under the regulation of HIV-1 Vpr.

Yuan T, Yao W, Huang F, Sun B, Yang R - PLoS ONE (2014)

Bottom Line:
In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts.Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB.These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes.

Affiliation: Research Group of HIV Molecular Epidemiology and Virology, Center for Emerging Infectious Diseases, The State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, The People's Republic of China.

ABSTRACTTRIM11 has been reported to be able to restrict HIV-1 replication, but the detailed aspects of the interfering mechanisms remain unclear. In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts. Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB. Deletion mutant experiments showed that the RING domain of TRIM11 was indispensable in inhibiting the early steps of HIV-1 transduction but was dispensable in decreasing NF-κB and LTR activities. Moreover, we found that low levels of Vpr decreased TRIM11 protein levels, while high levels increased them, and these regulations were independent of the VprBP-associated proteasome machinery. These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes. Thus, our work confirms TRIM11 as a host cellular factor that interferes with the early steps of HIV-1 replication and provides a connection between viral protein and host antiviral factors.

pone-0104269-g002: Effects of TRIM11 on the early steps of HIV-1 replication.A. HEK293 cells stably expressing TRIM11 or control pCDH vector were inoculated with 50 ng/ml (p24gag) of HIV-1 Vpr− viruses and analyzed by qPCR for late reverse transcripts and 2-LTR circle DNA at 24 hpi and integrated DNA at 14 day post infection (dpi). B. TRIM11 knock-down and control cell lines were inoculated with 50 ng/ml (p24gag) of HIV-1 Vpr− viruses and analyzed by qPCR for late reverse transcripts and 2-LTR circle DNA at 24 hpi and integrated DNA at 14 dpi. Error bars represent the standard deviations from three independent replicates of the same experiment. *P<0.05.

Mentions:
The transduction of HIV-1 in this study encompassed several events of the retroviral life cycle. To examine which events TRIM11 interfered with, we infected cell lines that stably expressed control vector or HA-TRIM11 with 50 ng/ml (p24gag) of HIV-1 Vpr−, and the different forms of the viral DNA (late reverse transcripts, 2-LTR DNA and integrated DNA) in the infected cells were quantified with relatively quantitative PCR. Surprisingly, the levels of all three forms of viral DNA were significantly lower in the TRIM11 overexpression cell line compared with the control cell line (Figure 2A). These results indicate that ectopic TRIM11 expression most likely inhibits the events of the HIV-1 replication cycle before retrotranscription, resulting in decreased late reverse transcripts and diminishing the levels of 2-LTR circle DNA and integrated viral DNA. Furthermore, we confirmed the above results using a TRIM11 knockdown cell line. Reducing TRIM11 can enhance the levels of viral reverse transcripts, 2-LTR circle DNA and integrated viral DNA (Figure 2B). In conclusion, TRIM11 may interfere with HIV-1 transduction by restricting the early steps before retrotranscription.

pone-0104269-g002: Effects of TRIM11 on the early steps of HIV-1 replication.A. HEK293 cells stably expressing TRIM11 or control pCDH vector were inoculated with 50 ng/ml (p24gag) of HIV-1 Vpr− viruses and analyzed by qPCR for late reverse transcripts and 2-LTR circle DNA at 24 hpi and integrated DNA at 14 day post infection (dpi). B. TRIM11 knock-down and control cell lines were inoculated with 50 ng/ml (p24gag) of HIV-1 Vpr− viruses and analyzed by qPCR for late reverse transcripts and 2-LTR circle DNA at 24 hpi and integrated DNA at 14 dpi. Error bars represent the standard deviations from three independent replicates of the same experiment. *P<0.05.

Mentions:
The transduction of HIV-1 in this study encompassed several events of the retroviral life cycle. To examine which events TRIM11 interfered with, we infected cell lines that stably expressed control vector or HA-TRIM11 with 50 ng/ml (p24gag) of HIV-1 Vpr−, and the different forms of the viral DNA (late reverse transcripts, 2-LTR DNA and integrated DNA) in the infected cells were quantified with relatively quantitative PCR. Surprisingly, the levels of all three forms of viral DNA were significantly lower in the TRIM11 overexpression cell line compared with the control cell line (Figure 2A). These results indicate that ectopic TRIM11 expression most likely inhibits the events of the HIV-1 replication cycle before retrotranscription, resulting in decreased late reverse transcripts and diminishing the levels of 2-LTR circle DNA and integrated viral DNA. Furthermore, we confirmed the above results using a TRIM11 knockdown cell line. Reducing TRIM11 can enhance the levels of viral reverse transcripts, 2-LTR circle DNA and integrated viral DNA (Figure 2B). In conclusion, TRIM11 may interfere with HIV-1 transduction by restricting the early steps before retrotranscription.

Bottom Line:
In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts.Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB.These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes.

Affiliation:
Research Group of HIV Molecular Epidemiology and Virology, Center for Emerging Infectious Diseases, The State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, The People's Republic of China.

ABSTRACTTRIM11 has been reported to be able to restrict HIV-1 replication, but the detailed aspects of the interfering mechanisms remain unclear. In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts. Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB. Deletion mutant experiments showed that the RING domain of TRIM11 was indispensable in inhibiting the early steps of HIV-1 transduction but was dispensable in decreasing NF-κB and LTR activities. Moreover, we found that low levels of Vpr decreased TRIM11 protein levels, while high levels increased them, and these regulations were independent of the VprBP-associated proteasome machinery. These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes. Thus, our work confirms TRIM11 as a host cellular factor that interferes with the early steps of HIV-1 replication and provides a connection between viral protein and host antiviral factors.